HI Steve. YT will not allow me to post a URL in this response but a cogaullee (John Petters) has posted videos in which demonstrates the powerline adapters fully communicating with each other without ANY physical connection, proving they are wireless telegraphy. He connected one adapter to a 12v inverter and the other to a petrol generator and each had a couple of extension leads and were fully balanced. The adapters still connected and we had a Skype call! Not secure!